The final data of the phase I/II clinical trial confirms 3.6 to 6 folds of neutralizing antibody titer compared to human convalescent sera
The trial data also proved immunogenicity to elders
The global phase III clinical trial is in progress with completion of enrolling about 500 participants in Korea

SK bioscience´s COVID-19 vaccine candidate has secured significant phase I/II clinical trial data. The expectation for the ´Korea’s First´ COVID-19 vaccine has grown even higher as the phase I/II clinical trial has been successfully completed while the phase III clinical trial is also being conducted.

SK bioscience (CEO Jae-yong Ahn) announced on November 4th that the company has confirmed a positive immune response and safety in the final analysis result of the phase I/II clinical trial of the COVID-19 vaccine candidate, ‘GBP510,’ co-developed with the Institute for Protein Design (IPD) at University of Washington School of Medicine in the U.S and adjuvanted with GlaxoSmithKline’s (GSK) pandemic adjuvant system.

SK bioscience enrolled 328 healthy adult participants to conduct the phase I/II clinical trial of GBP510 at 14 clinical institutions including Korea University Guro Hospital. As a result, the generation of the neutralizing antibodies against the COVID-19 virus has been confirmed in all participants receiving the adjuvanted vaccine, demonstrating a 99% seroconversion rate.

The observed neutralizing antibody titer after two weeks from the injection was about 6 times higher in a pseudovirion-based neutralization assay(PBNA) of the entire subject and about 3.6 times higher in a plaque reduction neutralization test(PRNT) of the subset compared to the serum panel of recovered COVID-19 patients. In addition, the IgG antibody titer was about 13.3 times higher in an enzyme-linked immunosorbent assay(ELISA) compared to the serum panel of recovered COVID-19 patients.

GBP510 which demonstrated a high level of neutralizing antibody induction in the phase I/II clinical trial, including the elders over 65 years old whose antibody response rate is usually low, indicated a similar or higher level of immunogenicity compared to the current COVID-19 vaccines.

This result shows that GBP510 proves significant efficacy in the humoral immune response which activates the production of antibodies, and in the cellular immune response which removes the infected cells. 

The result has been acquired by standardized analysis using international standard material and analytic method established by the World Health Organization (WHO) and the UK’s National Institute for Biological Standards and Control (NIBSC). The convalescent sera control is inclusive of the lowest to the highest levels of neutralizing antibody formation rates.

In terms of safety, no serious adverse events following immunization (AEFIs) were detected in relation to GBP510 injection, demonstrating sufficient tolerability.

SK bioscience will submit the positive data of the phase I/II clinical trial to domestic and international regulatory agencies and plan to further accelerate the development of GBP510 based on the results.

SK bioscience is currently planning to initiate the global phase III clinical trial across the regions including Europe and Southeast Asia, followed by Vietnam where the trial is being already conducted, with the International Vaccine Institute (IVI) in this month.

In South Korea, 14 clinical institutions including Korea University Guro Hospital are conducting the phase III clinical trial for GBP510 since August with enrolling about 500 participants, 5 times more population than originally planned.

Based on the data from the global phase III clinical trial targeting about 4,000 participants, SK bioscience will prepare to acquire an approval from South Korea’s Ministry of Food and Drug Safety (MFDS). Also, the company plans to receive WHO Pre-qualification (PQ) certification and emergency use authorization (EUA) by individual countries based on the result of the phase III clinical trial.

GBP510 was the first COVID-19 vaccine candidateed as a part of Wave 2, a project initiated by Coalition for Epidemic Preparedness Innovations (CEPI) in 2020 to support promising vaccine candidates. Following continued positive progress and market authorization, GBP510 will be made available to the COVAX Facility for procurement and equitable allocation worldwide. In addition, SK bioscience will supply GBP510 to the world, including Korea, by establishing its own distribution plans to individual countries through their approval process.

According to Our World in Data, a statistical site developed by a research team at Oxford University in the UK, only about 50% of the world´s population has received at least one dose of a COVID-19 vaccine, and the vaccination rate in low-income countries is only 3.7%, so the demand for the vaccine is still high. 

The synthetic antigen vaccine platform applied to the development of GBP510 allows it to be stored in normal refrigeration conditions under 2 to 8 degrees Celsius, so it can be distributed through the current vaccine logistics network with being stored for a long of time, securing wider accessibility.

Richard Hatchett, CEO at CEPI, said “SK bioscience’s phase 1/2 data for their COVID-19 vaccine are promising. It is vital that the world continues to invest in the critical R&D needed to develop next-generation COVID-19 vaccines. We have come a tremendous way in the fight against this pandemic and we cannot afford to lose on the gains we have made against this unforgiving virus. I look forward to continuing the collaboration between our two organisations and with the Republic of Korea to help bolster the world’s ability to control COVID-19”.

SK bioscience CEO Jaeyong Ahn said, “We were able to successfully manage the phase I/II clinical trial with close cooperation of public health officials including the COVID-19 Pan-government Support Committee, MOHW, MFDS, and the KDCA, as well as global civil and public entities, such as CEPI, Bill and Melinda Gate Foundation(BMGF) and IVI. As the phase 3 clinical trial is proceeding smoothly, we will develop GBP510 as quickly as possible to contribute overcoming the pandemic and securing the right to human health.”